The present invention relates generally to wireless communications, but more specifically to systems and methods for intelligent inter-system handoff in wireless communication internetworks.
The trend toward wireless communications is due to a number of sourcesxe2x80x94notably, the industrialized world""s increasingly mobile workforce. As well, low cost manufacturing and nearly free international trade make supplying the world""s hearty appetite for wireless products easier. Governments too, seem recently more amenable to loosing their grip on the electromagnetic spectrum.
But above all, consumer demand for instant and universal information access has fueled expansion of the wireless communication industry. In effort to keep pace, unfortunately, the global wireless infrastructure has become an intricate patchwork of largely non-cooperative solutions to localized problems. Worse, to meet the demand for more wireless capability, it is expected that the industry will proliferate, not consolidate, the number of wireless telecommunications standards.
Mobile devices with built-in multi-mode switching capability provided a first-cut stopgap solution to the interoperability problem with respect to Wireless Wide Area Networks (w-WANs). But while current-generation mobile devices ship with dual-mode capability (e.g. AMPS and CDMA), or possibly tri-mode capability, such systems are decidedly crude and inefficientxe2x80x94for instance, scanning continuously in search of a preferred network.
Further, because of the nature of the built-in multi-mode capability, such mobile units are still pre-configured to operate in a limited number of specific wireless communication networks. Thus, if one of these specific systems is not available then the mobile device will still not be able to acquire service even if another wireless communication network is available.
And, to be sure, the demand for wireless voice and data now extends well beyond telephones to include personal mobile communication devices of all types, including personal digital assistants. Hence, tomorrow""s mobile communication systems must improve multi-mode reliability for a variety of mobile types, while conserving a device""s precious MIPS, battery reserve, and the like.
Moreover, there is proliferation of Wireless Local Area Network (W-LANs) and Wireless Personal Area Networks (W-PANs) that are designed for efficient wireless communication over smaller areas, such as in an office building. Therefore, it would be advantageous for a mobile device to be able to switch from W-WAN operation to W-LAN or W-PAN operation when the latter is available. This could not only conserve battery power, but it could also provide other advantageous such as cost.
The systems and methods for intelligent inter-system handoff conserves mobile unit resources by performing a conditional scan, rather than a continuous background scan. In a region of overlapping coverage between competing wireless communication networks, a multi-mode mobile station switches from a non-preferred network to a preferred network contingent upon the presence of an entry in a roaming table. A roaming table is a lookup table having an entry corresponding to the presence or absence of a preferred network coverage area overlapping or completely contained within a cellular coverage area circumscribed by a non-preferred wireless communication network. A unique cell identifier assigned to each cell in the non-preferred network is used to find a match in the lookup table, which match signals an approval for the mobile station to initiate a search for the corresponding preferred network. The roaming table may be multi-dimensional as well, capable of supporting nested coverage areas.
In one embodiment, the systems and methods for intelligent inter-system roaming the roaming table includes position information for the available networks. The roaming table is then consulted after an accurate position determination for the mobile station has been secured via GPS fix, or other positioning system
In still other embodiments, the systems and methods for intelligent inter-system roaming garners intelligence by means of a learning function. The learning function algorithm records and learns the regular habits of its subscriber by profiling periodic activities, such as a subscriber""s regular commute to work, and modifies the scanning frequency accordingly. Efficient scanning, regulated by the learning function, results therefrom.
Finally, the systems and methods for intelligent inter-system handoff facilitates roaming to and from any one of a WAN, a LAN, or a PAN, giving the subscriber automatic cost savings by switching to a less expensive, higher speed network if one is available.
Other aspects, advantages, and novel features of the invention will become apparent from the following Detailed Description of Preferred Embodiments, when considered in conjunction with the accompanying drawings.